Editing Lockheed YF-12 (section)

==Design and development==
In the late 1950s, the [[United States Air Force]] (USAF) sought a replacement for its [[F-106 Delta Dart]] interceptor. As part of the Long Range Interceptor Experimental (LRI-X) program, the [[North American XF-108 Rapier]], an interceptor with Mach 3 speed, was selected. However, the F-108 program was canceled by the [[United States Department of Defense|Department of Defense]] in September 1959.<ref name=Pace_p45-6>Pace 2004, pp. 45–46.</ref> During this time, Lockheed's Skunk Works was developing the A-12 [[reconnaissance aircraft]] for the U.S. [[Central Intelligence Agency]] (CIA) under the ''Oxcart'' program. [[Kelly Johnson (engineer)|Kelly Johnson]], the head of Skunk Works, proposed to build a version of the A-12 named AF-12 by the company; the USAF ordered three AF-12s in mid-1960.<ref name=Pace_p46-7>Pace 2004, pp. 46–47.</ref>

[[File:YF-12 Forward Chine.jpg|thumb|Picture of the modified chine to accommodate the AN/ASG-18 radar]]
The AF-12s took the seventh through ninth slots on the A-12 assembly line; these were designated as ''YF-12A'' interceptors.<ref name=Land_Jenk_p40-1>Landis and Jenkins 2005, pp. 40–41.</ref> The main changes involved modifying the A-12's nose by cutting back the chines to accommodate the huge [[Hughes AN/ASG-18]] fire-control radar originally developed for the XF-108 with two [[infrared search and track]] sensors located in the chine leading edge, and the addition of the second cockpit for a crew member to operate the fire control radar for the [[air-to-air missile]] system.<ref name=airforcemag>{{cite magazine |last=Jn. |first=J. S. B. |date=November 1964 |title= Nine Times Better |url=http://www.airforcemag.com/MagazineArchive/Magazine%20Documents/1964/November%201964/1164YF-12.pdf |magazine=Air Force Magazine |publisher=USAF }}</ref> The modifications changed the aircraft's aerodynamics enough to require ventral fins to be mounted under the fuselage and engine nacelles to maintain stability. Three of the four bays previously used to house the A-12's reconnaissance equipment were converted to carry Hughes [[AIM-47 Falcon]] (GAR-9) missiles.<ref name=fighter/> One bay was used for fire control equipment.<ref>{{Cite web |url= http://www.designation-systems.net/dusrm/m-47.html |title= Hughes AIM-47 Falcon |publisher= Designation systems}}</ref>

[[File:Lockheed YF-12A 60-6934 in Air Defense Command markings 1963.jpg|thumb|Lockheed YF-12A, Serial# 60-6934, the only YF-12A in ADC markings]]
The first YF-12A flew on 7 August 1963.<ref name=fighter>Green and Swanborough, 1988, p. 350.</ref> President [[Lyndon B. Johnson]] announced the existence of the aircraft{{efn-ua|Johnson's speech named the plane A-11, the name for the two-seat design.}}<ref name=oxcartstory_p15>McIninch 1996, p. 15.</ref> on 24 February 1964.<ref name=museum>Air Force Museum Foundation, 1983, p. 133.</ref><ref name=oxcartstory_p14>McIninch 1996, p. 14.</ref> The YF-12A was announced in part to continue hiding the A-12, its still-secret ancestor; any sightings of CIA/Air Force A-12s based at [[Area 51]] in Nevada could be attributed to the well-publicized Air Force YF-12As based at [[Edwards Air Force Base]] in California.<ref name=oxcartstory_p15/> The first public showing of the aircraft was on 30&nbsp;September 1964 at&nbsp;Edwards.<ref name=srapunv>{{cite news |url=https://news.google.com/newspapers?id=PjlWAAAAIBAJ&sjid=regDAAAAIBAJ&pg=7229%2C11473 |work=Spokesman-Review |location=(Spokane, Washington) |agency=Associated Press |title=Super jet fighter unveiled by U.S. |date=1 October 1964 |page=1}}</ref>

On 14 May 1965, the Air Force placed a production order for 93 F-12Bs for its [[Aerospace Defense Command|Air Defense Command]] (ADC).<ref name=Pace_p53>Pace 2004, p. 53.</ref> However, [[United States Secretary of Defense|Secretary of Defense]] [[Robert McNamara]] would not release the funding for three consecutive years due to [[Vietnam War]] costs.<ref name=Pace_p53/> Updated intelligence placed a lower priority on defense of the continental US, so the F-12B was deemed no longer needed. Then in January 1968, the F-12B program was officially ended.<ref>Donald 2003, pp. 148, 150.</ref>